On Tue, 23 Aug 2022, Aldy Hernandez wrote: > On Tue, Aug 23, 2022 at 2:16 PM Richard Biener <rguent...@suse.de> wrote: > > > > The following reverts a hunk from r8-5789-g11ef0b22d68cd1 that > > made compute_control_dep_chain start from function entry rather > > than the immediate dominator of the source block of the edge with > > the undefined value on the PHI node. Reverting at that point > > does not reveal any testsuite FAIL, in particular the added > > testcase still passes. The following adjusts this to the other > > function that computes predicates that hold on the PHI incoming > > edges with undefined values, predicate::init_from_phi_def, which > > starts at the immediate dominator of the PHI. That's much less > > likely to run into the CFG walking limit. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu. > > > > Aldy - you did this change, do you remember anything here? In > > fact the whole thing that's now called predicate::use_cannot_happen > > seems to be redundant - the two testcases attributed to its history > > do not fail when that's disabled, nor did they fail when it was > > introduced. In principle whats now called predicate::superset_of > > should cover this (but different implementation limits might apply). > > OMG, I'm drawing a complete blank here. I have no recollection of > this. I'm tempted to say either my account was hacked or that old > code was all wrong ;-).
Eh. Pushed then. I'm going to baby-step changes so we can figure out things when later bisecting regressions ... Thanks, Richard.
